1. Field of the Invention
The present invention relates to a lockable door structure, and more particularly to a lockable door structure applicable to an electronic device, which can selectively cover an opening of a case of the electronic device.
2. Related Art
With the rapid development of the electronic technology, portable notebook computers with high mobility and convenience have gradually become the mainstream of the market. Since the notebook computer is small, and cannot be mounted with too may peripheral devices or connection ports, the notebook computer is usually required to be connected to various external peripheral devices through special expansion slots, so as to be highly applicable and highly extensible as a multifunctional product.
For the above extensible notebook computer, room is reserved inside the case of the mainframe of the notebook computer, so that peripheral hardware devices can be mounted inside the mainframe. The room is connected to the outside through an opening in the surface of the case, so that a user can directly mount or dismount a peripheral hardware device without disassembling the case, thus avoiding the trouble of dissembling the case of the mainframe.
When the notebook computer is used in a harsh and hostile environment, for example, in a case in which a military computer has to be used outdoors for a long period of time, foreign matter, such as dust, dirt, and liquid, has to be prevented from entering into the inside of the notebook computer through the expansion slots. Therefore, a movable door cover structure is designed in most existing notebook computers, so as to cover the expansion slots to make the notebook computer dustproof and waterproof. However, the door cover structure cannot harm convenience of a user using the notebook computer, so that the door cover structure for the dust proofing and the water proofing must take into account of both the convenience of use and the covering effect of preventing the foreign matters from entering.
Since water is in liquid form, water is easier to flow into the inside of the notebook computer as compared with foreign matter of solid form such as the dust. If water enters into the computer device, the water may directly damage electronic components of the computer device. Therefore, how to prevent the water from entering into the inside of the computer device is a major design consideration of research and development personnel.
In the prior art, a common door cover structure is similar to a gate. The gate-type waterproof door cover slides along a direction parallel to a sidewall of the case in a reciprocating manner, and the waterproof door cover can pivot relative to the computer device, so as to expose the expansion slots to the outside selectively. In addition, in order to enhance the waterproof of the door cover structure, in the prior art, a compressible waterproofing layer with friction is disposed between the waterproof door cover and the sidewall of the case, which for example, may be a foam material or a rubber material. The waterproofing layer is pressed tightly within limited room between the waterproof door cover and the case to prevent the water from passing through the room between the waterproof door cover and the case to flow into the inside of the computer device.
Conventionally, the waterproofing layer is usually made of a material with a high friction coefficient, so as to achieve an optimal waterproofing effect. However, high friction of the waterproofing layer also incurs friction to the sliding of the waterproof door cover, so that high friction of the waterproofing layer makes the sliding of the waterproof door cover difficult during opening and closing of the cover. In order to enhance the waterproofness of the door cover, the thickness of the waterproofing layer has to be increased to enhance the contact and an interference force between the waterproofing layer and the door cover, so that the thickness of the waterproofing layer increased makes the sliding of the waterproof door cover harder and results in inconvenience of the operation of the user.
On the contrary, in order to decrease resistance generated during the sliding of the waterproof door cover, the thickness of the waterproofing layer has to be decreased to make it easy for the door cover to slide. However, a distance between the waterproof door cover and the case remains the same, and therefore the waterproofing layer is no longer pressed tightly by the waterproof door cover, thus results in an imperfect waterproofing effect of the waterproof door cover.